The present invention relates to an alarm system and particularly, but not exclusively, to an improved form of alarm system for detecting smoke, fire, carbon monoxide or other noxious gases.
The use of carbon monoxide, smoke and fire detectors in homes has become increasingly common. Some systems have a number of remote sounders which can be triggered to emit a warning sound when a remote base station detects the presence of fire, smoke, carbon monoxide or the like. Such a remote sounder has the advantage that it can be placed at the bedside of, for example, a child.
However, research has shown that children particularly can be difficult to wake and often when they are woken by an alarm the main electrical system of the building may have been damaged and be inoperative and the room or a building may be filled with an appreciable quantity of smoke. The effect is to disorientate the occupants who can then find it difficult to escape from a dark, smoke filled area. This problem can be exacerbated if the fire occurs after dark.
The present invention seeks to provide an improved alarm system.
Accordingly, the present invention provides an alarm system comprising: an alarm handset having: a housing; a detector circuit having means for receiving a preselected signal from a remote transmitter and generating a first detection signal in response thereto; first sensing means for sensing change in a preselected parameter of the handset; light generating means for generating visible light; alarm means for generating an alarm signal; and control means responsive to receipt of said detection signal to activate said alarm circuit; wherein said control means is further operable to activate said light generating means in response to receipt of said control signal and subsequent sensing of said change in said preselected parameter of the handset.
In a preferred form of the invention said preselected parameter comprises one of a preselected time period following receipt of said control signal; actuation of a switch; or movement of said handset.
Advantageously, said system further comprises: cradle means for supporting said handset; and wherein said first sensing means comprises means for sensing the presence or absence of said handset in said cradle; and said control means is operable to activate said light generating means in response to said first sensing means sensing subsequent removal of said handset from said cradle.